House crow description

A relatively small crow (2)(6), the house crow (Corvus splendens) is a slim-bodied and somewhat leggy species (2)(5)(6)(7) with mostly black or blackish-slate plumage (2)(3)(6). Its scientific name means ‘shining raven’ (8), and refers to the glossy, jet-black feathers on the face, crown, chin and throat (2)(5).

A distinctive grey collar extends across the back and sides of the house crow’s neck and on its upper mantle(2)(3)(5)(6)(7), and this stands out sharply against the black plumage of the head (6). The underparts of the house crow are grey or blackish-grey (2)(5), and the relatively long, prominent bill is black and slightly arched (2)(3)(7). The house crow’s feet are also black, while its eyes are brown to dark brown (2)(3).

Male and female house crows are similar in appearance (2)(7), and juveniles can be distinguished by their duller plumage which lacks the glossy black sheen of the adults (2).

The four subspecies of house crow all differ slightly in colour. Corvus splendens zugmayeri is the palest, with an almost whitish-grey nape, and Corvus splendens insolens is the darkest, with a much less obvious contrast between the black and grey feathers (2).

A very noisy species, the house crow has a rather flat, dry call which is described as being a rather toneless ‘kaaan-kaaan’ or ‘kaa-kaao’. This species also makes a wide variety of softer, nasal calls in social interactions (2)(3). Interestingly, the calls of the subspeciesC. s. insolens are reported to be higher in pitch than those of the nominate subspecies(2).

Related species

House crow biology

A very intelligent species (5), the house crow is always alert and wary, walking or hopping along the ground with its wings flicking nervously (2). It is a social, non-migratory species which gathers in noisy flocks throughout the year and forms massive roosts (2)(3)(5)(6). Such flocks may number hundreds or thousands of individuals, and the house crow is known to gather together with groups of parakeets (Psittacidae) and mynahs (Sturnidae) in mangroves or plantations. The house crow flies back to its foraging grounds just before dawn breaks (2).

An omnivorous scavenger, the house crow has a varied diet, feeding on everything from carrion, seeds and nectar to invertebrates and small vertebrates(2)(4)(5)(6). This species tends to take advantage of rubbish tips, markets, farms, fisheries and abattoirs, scavenging for scraps and offal (2)(3)(4)(5), and even sometimes feeds on human corpses (2).

The house crow raids crops, damaging them by pulling seedlings up by the roots, and it is known to steal grain, rice and other food from buildings (2)(3)(5). This species also feeds on the eggs and nestlings of many bird species, such as those of herons and egrets, and its agility enables the house crow to enter weaver bird colonies. Aerial sallies are undertaken to pluck flying ants from the air, and fish and aquatic insects are snatched from the water following plunge-dive type movements. A bold and aggressive species, the house crow rides on the backs of large mammals to pick off ticks and other parasites, and it has also been reported to peck at any open sores within its reach (2).

The breeding season of the house crow varies depending on the geographic location (2). In many parts of its range, such as in India, the house crow breeds at the beginning of the wet season, from April to June (2)(6), whereas in East Africa this species breed between September and June (6). The house crow forms long-term pair bonds and is generally considered to be a monogamous species, but many individuals are reported to be rather promiscuous (2).

The house crow is usually a solitary nester (2)(6), and typically nests close to human habitation (5)(7). The untidy nests of the house crow are often built in trees, but are also found on building ledges, electricity pylons and streetlamps (2)(5)(6)(7). Nests may be made of sticks and twigs, or from man-made materials such as metal and wire gathered from rubbish tips (2)(5)(7), and are usually lined with soft materials (2). A wire nest can weigh up to an impressive 25 kilograms. Although both sexes collect the nest material, it is usually the female that builds the nest (2).

The female house crow lays three to five eggs per clutch (6)(7), with an average of four (2), and the eggs are extremely variable both in shape and colour (7). Incubation lasts 16 to 17 days, and is thought to be carried out by the female alone, although the male may relieve her for short periods. House crow chicks are fed by both parents, and remain in the nest for three to four weeks (2). The house crow may produce two clutches of eggs per breeding season (2)(6).

In its native range, the house crow is known to be predated by other corvids, birds of prey, snakes and monkeys. However, it has few predators in many areas where it has been introduced (6).

House crow range

Widely distributed in southern Asia (5), the house crow occurs from southern Iran eastwards through Pakistan, India and Bangladesh to southern Tibet, south-western China and central Thailand (3)(6)(9)(10). This species is also found on the Maldives (2)(6)(9).

In addition, the house crow has been introduced to parts of Africa, the Middle East, Europe and several islands, including Mauritius (3)(4)(5)(9). In many areas, it is thought that the species was introduced as a result of it stowing away on boats (3)(6), and it is the only known alien species to be ‘self-introduced’ in southern Africa (11). However, deliberate introductions have been known in Africa and Southeast Asia as a means of controlling insect pests or clearing streets of food waste (6). The house crow is also considered to be a vagrant in some countries, including Cambodia, Japan, Denmark and the United Kingdom (10).

The four subspecies of house crow all have slightly different distributions. For instance, Corvus splendens splendens is found throughout most of peninsular India, as well as in Nepal, Bhutan and Bangladesh, whereas Corvus splendens insolens is found in extreme southern China and Myanmar (2).

Species with a similar range

House crow habitat

The house crow is strongly associated with human habitation (2)(6)(9), being found in villages, towns and cities (2)(3)(4)(9). Interestingly, no populations of this species are known to live independently of people (6).

Found in tropical and subtropical areas (2), the house crow is generally a lowland species (9), often occurring at elevations below about 1,600 metres (2). However, it has been reported in Himalayan military bases at elevations of up to 4,240 metres (2).

Species found in a similar habitat

House crow status

House crow threats

The house crow is abundant throughout its extremely large range, and is not considered to be globally threatened (2)(10).

However, in many areas where the house crow has been introduced, colonies of this species have reached pest proportions, spreading rapidly (2)(6)(7) and being regarded as invasive (6). The house crow inflicts economic damage by destroying fruit and crops such as wheat and maize (2)(6)(7), and also through preying on the chicks and eggs of domestic poultry (2). Even within its native range this species is sometimes considered to be an agricultural pest (7).

As a predator of other bird species, the house crow is also responsible for displacing native bird species through aggressive competition (6)(7). In addition to the threats it poses to native wildlife in its introduced range, the house crow is also believed to be a risk to human health, as it is known to carry several human pathogens including Salmonella and E. coli(2)(6). This invasive species has become a nuisance in many areas, and has even threatened tourist amenities in certain regions (2)(6). The lack of natural predators in its introduced range prevents the limitation of house crow numbers (2).

Although the house crow has not yet been recorded in the UK, this destructive species is expected to arrive in the country in the future, potentially through natural spread from the Netherlands, where a small breeding population has established itself (6).

House crow conservation

The house crow is not currently considered to be threatened, and as a result there are no known conservation measures in place for this species.

However, in some countries where the house crow has been introduced and is considered to be an invasive species, various methods have been employed to control or eradicate it. In Kenya, Tanzania and South Africa, the house crow is controlled through trapping, poisoning and destroying nests, whereas in Australia there is a ‘shoot on sight’ policy which may help prevent the species from becoming established in the country and threatening Australia’s native birds (2).

On Socotra, where a population of more than ten breeding pairs of house crows became established, threatening the island’s native biodiversity, an inventive scheme was introduced to control the invasive species. Local children were paid to take house crow nests containing young to the Socotra Archipelago Conservation and Development Programme. The last crows on the island were killed by a marksman in 2009 (2).

In birds, the wings, shoulder feathers and back, when coloured differently from the rest of the body.

Monogamous

Having only one mate during a breeding season, or throughout the breeding life of a pair.

Nape

The back of the neck.

Nominate subspecies

When a species is divided into subspecies, the originally described population is classified as the nominate subspecies. Indicated by the repetition of the species name; for example, Cyclura nubila nubila is the nominate subspecies of the Cayman Islands ground iguana, Cyclura nubila.

Omnivorous

Feeding on both plants and animals.

Parasite

An organism that derives its food from, and lives in or on, another living organism at the host’s expense.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Vagrant

An individual found outside the normal range of the species.

Vertebrate

An animal with a backbone, including mammals, birds, reptiles, amphibians and fish.

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